Divers conducting routine repairs at a federally recognized dam in Mobile, Alabama discovered a hidden grenade-type improvised explosive device at the Converse Reservoir, prompting an emergency response.

The Mobile Area Water and Sewer System (MAWSS) and the Mobile County Sheriff’s Office coordinated with multiple federal and local agencies to safely recover and detonate the device.

Bomb squads, including the FBI and state explosive ordnance teams, carried out the controlled destruction without reported injuries or damage to the water supply.

Officials said the device posed a serious but contained threat and was discovered before it could cause harm to the drinking water system, AL.com has reported.

Authorities have notified the U.S. Department of Homeland Security and plan to increase security at the reservoir following the incident.